Most high performance portable electronic devices rely on rechargeable battery packs to supply the power required for portable operation. The variety of battery packs has increased over time and continues to grow; for instance, numerous different battery cell chemistries have been employed such as Lithium, Nickel Cadmium (NiCd), Nickel Metal Hydride (NiMH), and Alkaline. These battery cells are typically assembled into battery packs having various numbers of cells and overall capacities. Different battery pack types typically have different charge capacities and optimum charging profiles. Attempting to recharge a battery pack using a different profile may not only diminish battery life and efficiency, but may also create a hazard due to overcharging and overheating.
Several approaches have been taken to allow a single battery pack charger to be able to safely charge a variety of battery pack types. First, the battery chargers may have their charge parameters set to the lowest common denominator for all the possible battery packs that may be attached to the charger; however, this approach leads to less than optimum charging in most situations. Second, the battery chargers may be equipped with expensive control circuitry to identify the battery pack type and set the charge parameters accordingly. However, this approach does not easily allow the use multiple charge profiles for the same battery pack type, such as a fast recharge and a slow recharge. Third, some battery chargers are equipped with a manual switch that a user can use to select the appropriate charge settings. However, these manual switches remain in the selected position until changed by the user; this may lead to unsafe charging when the user forgets to change the selection when changing battery pack types.
Thus, none of the prior art approaches have proven completely satisfactory and there remains a need for a battery charger which can provide multiple types of charges in a safe manner.